Chaweewan Jansakul

Isoflavone glycosides from Derris scandens

Five isoflavone glycosides, named derriscandenosides A-E (1-5), were isolated from the stems of Derris scandens, together with ten known compounds comprising one isoflavone, two benzoic acid derivatives, three glucosyl isoflavones and four rhamnosyl-(1-->6)-glucosyl isoflavones. The structures of the glycosides were assigned on the basis of spectroscopic data, especially of the acetate derivatives. Three known rhamnosyl-(1-->6)-glucosyl isoflavones isolated from a crude fraction were retested for hypotensive activity with varying results.

Hypotensive activity of an n-butanol extract and their purified compounds from leaves of Phyllanthus acidus (L.) Skeels in rats.

We aimed to investigate the effects, identify the active substances and establish the mechanisms involved in the hypotensive activity of an n-butanol extract from leaves of Phyllanthus acidus (PA extract). PA extract caused a decrease in blood pressure of anesthetized rats that was not modified by atropine or propranolol. PA extract caused a persistent dilatation of thoracic aortic rings preconstricted with either phenylephrine or KCl, and these effects were not modified by LNA or removal of the vascular endothelium. For phenylephrine-preconstricted aortic rings, the dilatory activity of the PA extract was not modified by atropine, propranolol or indomethacin. TEA, glybenclamide or ODQ significantly inhibited the dilatory activity of the PA extract on endothelium-denuded aortic rings. Nifedipine or a Ca(2+)-free medium depressed the aortic rings constrictor response to phenylephrine, and that was further augmented by the PA extract. Adenosine, 4-hydroxybenzoic acid, caffeic acid, hypogallic acid, and kaempferol were isolated from the PA extract. Each caused a decrease in blood pressure and dilatation of the aortic rings. LNA or removal of the endothelium reduced this activity. ODQ and TEA attenuated the vasodilatory activity of adenosine whereas glybenclamide and ODQ attenuated the effect of hypogallic acid. These results suggest that the hypotensive activities of the PA extract is likely the result of the direct action of these five compounds on the blood vessels by stimulating release of nitric oxide from the vascular endothelium, in part through stimulation of soluble guanylate cyclase, and opening of K(ATP) and K(Ca) channels in the vascular smooth muscle.

Crude extract and purified components isolated from the stems of Tinospora crispa exhibit positive inotropic effects on the isolated left atrium of rats.

ETHNOPHARMACOLOGICAL RELEVANCE Tinospora crispa has been used in folkloric medicine for the control of blood pressure. We previously found that an extract of Tinospora crispa and its constituents effect the heart rate and blood pressure in anesthetized rats. AIM OF THE STUDY The aim was to investigate the effects and mechanisms of the Tinospora crispa extract and bioactive components on the rat isolated left atria. MATERIALS AND METHODS Air-dried stems of Tinospora crispa were extracted with water, followed by partitioning with chloroform, ethyl acetate, and finally by n-butanol. The n-butanol soluble material was concentrated and dried under reduced pressure and lyophilized to obtain a crude powder (Tinospora crispa extract). The active components of Tinospora crispa extract were separated by column chromatography and preparative HPLC. The effects and mechanisms of the n-butanol extract and the bioactive purified components (adenine, uridine, adenosine, salsolinol, tyramine, higenamine, syringin, (-)-litcubinine, borapetoside A, borapetoside B, borapetoside D and borapetoside E) were studied in isolated left atria from normal and reserpinized rats. RESULTS Tinospora crispa extract caused an increase in the force of contraction of the electrical field stimulated left atrium. This effect was inhibited by propranolol, atenolol, ICI-118,551, phentolamine and atropine. The positive inotropic effect on the reserpenized isolated left atrium of the Tinospora crispa extract was significantly inhibited by propranolol, atenolol and ICI-118,551. Phentolamine, on the other hand, caused potentiation and the effect was inhibited when propranolol was also added. Higenamine caused an increase in the force of contraction of the electrical field stimulated left atrium and this effect was significantly inhibited by ICI-118,551 and atenolol but not by phentolamine. Reserpine did not significantly shift the concentration-response curve (C-R curve) of the inotropic effect of the higenamine. ICI-118,551 and atenolol caused a parallel shift of the C-R curve to the right of about 8 and 33 fold, respectively. At low concentrations salsolinol caused a slight increase in the force of contraction of the left atrium, but at higher concentrations a decrease was observed. The negative inotropic effect of salsolinol was significantly inhibited by propranolol and atropine. In the reserpinized isolated left atrium, the negative inotropic effect of salsolinol was potentiated and again this effect was significantly inhibited by propranolol and atropine. Tyramine caused a positive inotropic effect, and this effect was inhibited by propranolol or by pretreatment of the rat with reserpine. Adenosine caused a negative inotropic effect, while uridine caused a slight positive inotropic effect on the left atrium. This effect was significantly inhibited by DPCPX. CONCLUSIONS Crude extract of Tinospora crispa exert a positive inotropic effect on the electrical field stimulated isolated left atria that results from the concerted action of 5 bioactive compounds: higenamine, salsolinol, tyramine, adenosine and uridine. Higenamine, salsolinol (at low concentration) and tyramine acted via the adrenergic receptors to increase the force of the atrial contraction, whereas a high concentration of salsolinol acted indirectly by stimulating the release of acetylcholine. Adenosine and uridine acted via the purinergic pathways to cause negative inotropic effects on the isolated left atria.

Enhanced dissolution and oral bioavailability of nifedipine by spontaneous emulsifying powders: effect of solid carriers and dietary state.

The objective of this study was to prepare spontaneous emulsifying powder (SEP) for improving dissolution and enhancing oral bioavailability of a poorly water-soluble drug, nifedipine (NDP). In order to investigate the effects of solid carrier properties, such as surface area and pore size, and a concurrent food intake on absorption of NDP in rats, different SEP formulations were prepared by adsorbing liquid spontaneous emulsifying formulation (SEF), composing of polyoxyl 35 castor oil, caprylic/capric glyceride and diethylene glycol monoethyl ether at a ratio of 1:1:8, onto various solid carriers (i.e., silica (FS), porous calcium silicate (PCS) and porous silicon dioxide). The solid characterization by scanning electron microscopy, differential scanning calorimetry and powder X-ray diffraction revealed the absence of crystalline NDP in the formulations. SEP also demonstrated excellent spontaneous emulsification properties similar to SEF. The droplet size of emulsions formed after dilution was less than 200 nm. The solid carriers (particularly PCS) had significant and positive effect in drug dissolution; the mean dissolution time of SEP containing PCS was considerably improved. SEP also provided a good stability after storage in accelerated and long-term conditions for 6 months. The bioavailability study resulted in enhanced values of C(max) and AUC for SEP formulations, when tested in both fasted and fed rats. Furthermore, comparing the AUC in fasted and fed rats, NDP powder exhibited a significant food effect. The difference in bioavailability of NDP in fed compared to fasted state can be avoided by using SEP.

Effects of an n-butanol extract from the stem of Tinospora crispa on blood pressure and heart rate in anesthetized rats

ETHNOPHARMACOLOGICAL RELEVANCE Tinospora crispa has been used in folkloric medicine for control of blood pressure, as an antipyretic, for cooling down the body temperature and for maintaining good health. AIM OF THE STUDY To investigate the effects and mechanisms of action of an n-butanol extract from the stems of Tinospora crispa (T. crispa extract) on blood pressure and heart rate in anesthetized rats. MATERIALS AND METHODS Air-dried stems of T. crispa were extracted with water, followed by partitioned extract with chloroform, ethyl acetate, and finally by n-butanol. The n-butanol soluble part was evaporated under reduced pressure and lyophilization to obtain a crude dried powder (T. crispa extract). The effects and mechanisms of the T. crispa extract on blood pressure and heart rate were studied in anesthetized normal and reserpinized rats in vivo in the presence of different antagonists. RESULTS T. crispa extract (1-100 mg/kg, i.v.) caused a decrease in mean arterial blood pressure (MAP) and this effect was inhibited by propranolol, phentolamine, atenolol and/or the β(2)-antagonist ICI-118,551, but not by atropine or hexamethonium. In reserpinized rats, the T. crispa extract had a dual effect: reduction in hypotensive activity, followed by a small increase in blood pressure. The decrease in MAP in reserpinized rat was slightly potentiated by phentolamine, but inhibited by propranolol or ICI-118,551 only if atenolol and phentolamine were also present. The increase in MAP was potentiated by propranolol and ICI-118,551, but was inhibited by phentolamine. The T. crispa extract had a dual effect on heart rate in the normal rat: a small transient decrease, followed by an increase in heart rate. The positive chronotropic effect of T. crispa extract was inhibited by propranolol, phentolamine and atenolol, but not by ICI-118,551, atropine or hexamethonium. Reserpine potentiated the positive chronotropic effect of the T. crispa extract and this effect was inhibited by propranolol, atenolol and ICI-118,551, but not by phentolamine. CONCLUSIONS From these results we suggest that T. crispa extract possesses at least three different cardiovascular-active components that act directly via (1) β(2)-adrenergic receptors to cause a decrease in blood pressure, and β(1)- and β(2)-adrenergic receptors to cause an increase in heart rate, (2) α-adrenergic receptors to cause an increase in blood pressure and heart rate, and (3) a non-adrenergic and non-cholinergic pathway to cause a decrease in MAP and heart rate. These findings provide scientific support for the tradition of using this plant to modify the actions of the human cardiovascular system.

Hypotensive and cardio-chronotropic constituents of Tinospora crispa and mechanisms of action on the cardiovascular system in anesthetized rats.

ETHNOPHARMACOLOGICAL RELEVANCE Tinospora crispa has been used in folkloric medicine for the control of blood pressure. We previously found that an extract of Tinospora crispa stems decreased the mean arterial blood pressure (MAP) with a transient decrease, followed by an increase in the heart rate (HR) in rats. AIM OF THE STUDY To identify the active components of the Tinospora crispa extract and investigate the mechanisms of action on blood pressure and heart rate in anesthetized rats. MATERIALS AND METHODS The active components of Tinospora crispa extract were separated by column chromatography and a preparative HPLC. The effects and mechanisms of the active compounds on blood pressure and heart rate were studied in anesthetized, normal and reserpinized rats in vivo. RESULTS 5 active compounds: adenosine, uridine, salsolinol, higenamine and tyramine were isolated. Adenosine decreased MAP and HR and this effect was inhibited by DMPX (A(2A) adenosine receptor antagonist). Uridine increased MAP and decreased HR and this was inhibited by suramin but not by DMPX. Salsolinol decreased the MAP and HR and this was inhibited by phentolamine but not by ICI-118,551 (β(2)-adrenoceptor antagonist) or atropine. In reserpinized rats, salsolinol had a hypertensive effect that was inhibited by prazosin and phentolamine, but not by atenolol, and caused an increase in HR that was inhibited by atenolol, but not by prazosin or phentolamine. Higenamine decreased the MAP with an increase in HR. The hypotensive effect was inhibited by ICI-118,551 or atenolol, whereas the increase in HR was not inhibited by ICI-118,551. Atenolol inhibited the increase in HR at a small dosage of higenamine but potentiated it at a higher dosage. In reserpinized rats, a small dosage of higenamine tended to potentiate the effect but at a higher dosage it caused inhibition. ICI-118,551 significantly inhibited this hypotensive effect. Tyramine caused an increase in MAP and HR and these effects almost disappeared in reserpinized rats. CONCLUSIONS The results demonstrate that these 5 compounds from Tinospora crispa acted in concert on the cardiovascular system of anesthetized rats. Salsolinol, tyramine and higenamine acted via the adrenoreceptors, whereas uridine and adenosine acted via the purinergic adenosine A(2) and P(2) receptors to decrease blood pressure with a transient decrease of HR followed by an increase.

Effects of Kaempferia parviflora rhizomes dichloromethane extract on vascular functions in middle-aged male rat.

ETHNOPHARMACOLOGICAL RELEVANCE In Thai traditional medicine, rhizomes of Kaempferia parviflora (KP) have been used for treating hypertension and for the promotion of longevity with good health and well being. Ageing is one of the most important risk factors for development of cardiovascular disease. To investigate whether a 6 weeks oral administration of a dichloromethane extract of fresh rhizomes of Kaempferia parviflora (KPD) had any effects on vascular functions, on the accumulation of lipid, as well as on any signs of gross organ toxicity in middle-aged rats. MATERIALS AND METHODS Fresh rhizomes of Kaempferia parviflora were first macerated twice with 95% ethanol to remove the dark color before extracting three times with 100% dichloromethane. The dichloromethane extract was evaporated under reduced pressure to obtain the dried Kaempferia parviflora dichloromethane extract (KPD). The rats were orally administered with the KPD at a dosage of 100mg/kg body weight, or with the same volume of the vehicle (tween 80, 0.2g: carboxy-methylcellulose sodium, 0.2g: distilled water 10 ml) once or twice a day for 6 weeks. Vascular functions were studied on isolated thoracic aorta and the mesenteric artery. The vascular eNOS enzyme was measured by Western blot analysis. Blood chemistry was measured by enzymatic methods. Liver cell lipid accumulation was measured using oil red O staining. RESULTS A 6 weeks treatment of KPD once a day had no significant effects on any of the studied parameters. When the KPD was given twice a day, the contractile responses to phenylephrine of the thoracic aorta and mesenteric artery were lower than the vehicle control group, and this effect was abolished by N(G)-nitro-l-arginine or by removal of the vascular endothelium. Vasorelaxation to acetylcholine, but not to glyceryl trinitrate, by the thoracic aortic and mesenteric ring precontracted with phenylephrine was higher from the KPD treated rats than those from the vehicle control groups. Western blot analysis showed a higher quantity of thoracic- and mesenteric-eNOS protein obtained from the KPD treated rats. In addition, the body weight, serum glucose and triglycerides levels, visceral and subcutaneous fat, as well as liver lipid accumulation were all significantly decreased in the KPD treated rats compared to those of the vehicle control. No differences were found between the KPD treated-, and the vehicle-control for animal food intake, internal organ weight, serum ALP, SGOT, SGPT, BUN and creatinine levels, serum cholesterol, HDL-C and LDL-C levels, nor total blood cell counts. CONCLUSIONS The chronic oral administration of KPD extract, to middle aged rats, caused a decrease in vascular responsiveness to phenylephrine with an increase in the acetylcholine induced vasorelaxation, due to an increase in nitric oxide production from their blood vessels. The extract also caused a decrease in visceral and subcutaneous fat, fasting serum glucose and triglyceride levels and liver lipid accumulation, with no changes to liver and kidney functions or to total blood cell counts. It is possible that these KPD extracts could be developed as a health product for mid-aged humans to reduce obesity, diabetes type II and cardiovascular disease.

Six weeks oral gavage of a Phyllanthus acidus leaf water extract decreased visceral fat, the serum lipid profile and liver lipid accumulation in middle-aged male rats

ETHNOPHARMACOLOGICAL RELEVANCE Advancing age is associated with an increased accumulation of visceral fat and liver lipid which is then responsible for an age-related risk for cardiovascular disease. Looking after ourselves well with suitable micronutrients could prevent disease or prolong our healthy cardiovascular functions. In Thai traditional medicine, leaves of Phyllanthus acidus (PA) have been used for many purposes including as an antihypertensive agent and to provide relief from a headache caused by hypertension. We aimed to investigate the effects of a chronic oral administration of PA extracts to middle-aged (12-14 months) rats on their body weight, food intake, body fats, liver and kidney functions, fasting blood glucose and lipid profiles, liver lipid accumulation and on blood pressure. MATERIALS AND METHODS Three different kinds of PA extracts were used: (1) a PA water extract, (2) a heated PA water extract, and (3) an n-butanol fraction of the PA water extract, prepared from fresh leaves of Phyllanthus acidus. The rats were orally gavaged with the three PA extracts at 1.0 g/kg body weight or, as a control, with distilled water once a day for 6 weeks. Fasting blood sugar, lipid profile and ALP, SGOT, SGPT, BUN and creatinine levels were measured by enzymatic methods. Liver lipid accumulation was measured using oil red O staining on fresh thin cryostat liver tissue sections. The animal basal blood pressure and heart rate were measured in anesthetized rats via a common carotid artery using a polygraph. RESULTS Results showed that after 6 weeks of treatment using gavaged heated PA extract and PA n-butanol extract there were no changes in any of the parameters studied. However, the initial PA water extract caused a slight decrease in the animal body weight with no change in food intake. No changes were observed in the liver and kidney functions (serum ALP, SGOT, SGPT, BUN and creatinine did not change), nor did the fasting blood sugar or triglyceride levels differ significantly. Serum cholesterol, HDL and LDL levels, as well as visceral and subcutaneous adipose tissue and liver lipid accumulation were significantly decreased compared to that of the control group. There were no differences found in the basal systolic and diastolic blood pressure and the basal heart rate between the PA water extract treatment and the control group. CONCLUSIONS These results indicated that the PA water extract had an effect on lipid metabolisms that resulted in a decrease of the serum lipid profile, visceral and subcutaneous fat, as well as on liver lipid accumulation in middle-aged rats. The active component that is responsible for these effects is likely to be a water soluble substance(s) and is heat labile. As a consequence of these beneficial effects of the PA water extract, it would be a good choice for further development for use as a nutraceutical or health product to prevent and/or to slow down the development of obesity and/or cardiovascular disease.

Effects of 6 weeks oral administration of Phyllanthus acidus leaf water extract on the vascular functions of middle-aged male rats.

ETHNOPHARMACOLOGICAL RELEVANCE Leaves of Phyllanthus acidus (PA) have been used in Thai traditional medicine for the treatment of hypertension. We have previously shown that chronic treatment of a PA water extract to middle-aged male rats caused a lowering of the body and serum lipids, two of the parameters that are implicated in cardiovascular disease. AIM OF THE STUDY To investigate if chronic treatment of middle-aged male rats with a PA water extract affected the perivascular (aortic) adipose tissue (PVAT) and/or their vascular functions MATERIALS AND METHODS Fresh leaves of PA were extracted with water and orally gavaged to the middle-aged male rats for 6 weeks. Vascular functions were studied in vitro using isolated thoracic aorta with and without PVAT, and mesenteric rings in Krebs Heinseleit solution with results recorded with a Polygraph or a Myograph system. The amount of blood vessel eNOS and CSE (cystathionine-γ-lyase) expression was measured by Western blotting. RESULTS PA treatment caused a lower maximal contractile response to phenylephrine (Phe) of the endothelium-intact aortic ring than that of the control group. This effect was abolished by N(G)-nitro-l-arginine (l-NA) or by denudation of the endothelium. dl-propargylglycine (PAG, H2S inhibitor) and TEA (Ca(2+)-activated K(+) channel blocker), but not glybenclamide (ATP-activated K(+) channel blocker), caused a similar increase in the baseline of the endothelium-intact aortic ring in the presence of l-NA in both the PA-treated and control aortic rings. This effect sequentially resulted in a greater contractile response of the aortic rings of both groups to Phe. Glybenclamide also caused a similar increase in the maximal contraction of the endothelium-intact blood vessels with l-NA to both groups. PAG, TEA or glybenclamide did not modify the phenylephrine C-R curves for either group of the PVAT-endothelium-intact aortic rings preincubated with l-NA. The CSE levels of the thoracic aorta and at the PVAT were not different between the PA-treated and the control group. Relaxation of the Phe-precontracted thoracic aortic ring to acetylcholine, but not to glyceryl trinitrate, was higher for the PA-treated than for the control aortic rings and this effect was abolished by l-NA. The mesenteric rings of the PA treated group showed a lower sensitivity on the contractile response to Phe than that of the control group, and this effect was abolished by l-NA. Vasodilatation to acetylcholine, but not to glyceryl trinitrate, of the PA treated-mesenteric ring was more sensitive than that of the control group and this effect was abolished by l-NA. The expression of eNOS by the PA treated thoracic aorta and the mesenteric arteries was higher than the control group. These results demonstrated that chronic treatment with a PA water extract to middle-aged rats affected their vascular functions by increasing the nitric oxide production from the endothelial cells and also modulated the responsiveness of the thoracic aortic- and mesenteric rings to phenylephrine and acetylcholine.

Improved dissolution of Kaempferia parviflora extract for oral administration by preparing solid dispersion via solvent evaporation

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